Experimental investigation on the post-fire mechanical properties of the different weld metals

Nowadays, different types of welds and electrodes are used for welding in steel structures, each of which has different characteristics and performance. On the other hand, considering the general weakness of various steel elements such as welds in steel structures at high temperatures, it is very important to know their performance. Considering the insufficient research studies on the weld metals, in this study, the performances of weld metals made from welding with E6013, E7018, S2(EM12) and SG2(ER70S-6) after exposure to different temperatures are investigated. For this purpose, after welding the steel plates (ST37), the welds are turned into dumbbell-shaped specimens and then, exposed to elevated temperatures of 25, 100, 250, 400, 500, 700 and 900°C. afterward, when the specimens were naturally cooled to ambient temperature, tensile tests were carried out on them to obtain the stress-strain curves. The results indicate that in general, increase in the temperature undermines the mechanical properties (i.e. ultimate strength, yield strength and modulus of elasticity) of the weld specimens. It was found that the strength decreases more significantly at temperatures above 500 degrees. In addition, it was observed that ductility increases at temperatures above 700°C. Finally, comparison of the performance of the four weld metals, failure modes and energy absorption at various temperatures are the other results obtained in the present study. Accordingly, the temperature-dependent equations are proposed in order to predict the mechanical properties of the weld metals.